The aggressive behaviour of individual male polecats (Mustela putorius, M. furo and hybrids) towards familiar and unfamiliar opponents

Experiments are described which were designed to investigate the significance of individual differences in aggressiveness between polecats and the relation between the familiarity of the opponent and the pattern and outcome of fighting.
The behaviour of Mustela putorius, M. furo and hybrids between the two species was investigated in an indoor arena of 16 m².
Two kinds of fighting between male polecats were recorded, "companion fighting" between cage mates, in which biting was inhibited and neither of the opponents became intimidated and "uninhibited fighting" between unfamiliar individuals from which a winner and loser generally emerged and a rank order formed.
Individual differences in aggressiveness were assessed by means of a scoring system which statistical analysis showed, generally, to be consistent for any one individual. The rank of an animal, however, was found not to be invariably related to its aggression score.
A number of other factors influencing fighting were investigated, the earlier introduction of one individual into the arena increases its chances of winning a fight; when offered a choice, male polecats fight strangers in preference to cage mates; and the separation of a group of cage mates for as little as 48 hours induces them to behave towards one another like strangers with the result that a rank order is formed. Factors which had no apparent effect on fighting between males were the weight of the individual or the presence of females.
The attributes of familiar and unfamiliar opponents are discussed in the light of these findings.     

Regulation of natural killer cell activity by macrophages in the rheumatoid joint and peripheral blood

Recently, in another study, we observed that indomethacin, a prostaglandin synthetase inhibitor, significantly increased NK activity in both normal and rheumatoid arthritis (RA) peripheral blood (PB) but not in RA synovial fluid (SF). Because macrophages are a major source of prostaglandins, we examined the effect of macrophage-enriched adherent cells (AC) on NK activity as measured by a 3-hr Cr-release assay with K 562 cells. The removal of AC resulted in increased (p less than 0.01) NK activity in both normal and RA PB. In contrast, the removal of AC from RA SF resulted in a significant decrease (p less than 0.001) of NK activity. By using only nonadherent cells (NAC), NK activity in RA SF and synovial tissue (ST) was significantly reduced when compared to autologous RA PB (p less than 0.001). Enhancement of NK activity of SF NAC by both poly I:C and IL 2 was not dependent on AC. Mixing experiments demonstrated that the addition of synovial AC for 16 hr increased NK activity of synovial NAC to a level similar to that of unseparated mononuclear cells, whereas autologous PB AC suppressed NK activity of PB NAC. PB AC, when added to SF NAC, also increased NK activity. Supernatants from synovial mononuclear cells were stimulatory of synovial NAC NK activity, whereas normal PB mononuclear supernatants were suppressive. These observations document 1) a significant reduction of NAC-mediated NK activity in the rheumatoid joint as compared to PB from the same patient, and 2) that AC modulate NK activity differently in the rheumatoid joint as compared to RA or normal PB.     

Implication of growth hormone in experimental induction of vitellogenesis by estradiol-17 beta in female silver eel (Anguilla anguilla L.)]

The effect of different preparations of growth hormone (GH) was assayed with 17 beta-estradiol on vitellogenesis in hypophysectomized or normal female silver eels. Vitellogenin (Vg) plasma levels were taken as the index of hepatic vitellogenesis. The E2 doses were chosen to give the same pattern for the plasma Vg level as in the controls. They decreased or remained undetectable in hypophysectomized or normal animals. GH also failed to induce alone a significant modification. When E2 was injected together with a GH, plasma Vg levels were 5.13 +/- 1.30 times higher with salmon GH in hypophysectomized eels and 2.01 +/- 0.25 times higher with bovine GH in normal eels. GH is shown to enhance the effects of E2 on hepatic vitellogenesis induction in a teleost.     

When Landscaping Goes Bad: The Incipient Invasion of Mahonia bealei in the Southeastern United States

Woodlots are forest islands embedded within an urban matrix, and often represent the only natural areas remaining in suburban areas. Woodlots represent critical conservation areas for native plants, and are important habitat for wildlife in urban areas. Invasion by non-indigenous (NIS) plants can alter ecological structure and function, and may be especially severe in remnant forests where NIS propagule pressure is high. Woody shrubs in the Family Berberidaceae have been well documented as invaders of the forest–urban matrix in North America. Mahonia bealei (Berberidaceae) is a clonal shrub native to China, and is a popular ornamental in the Southeastern United States. Mahoni bealei is listed as “present” on some local and state floras, but almost nothing is known regarding its invasion potential in the United States. We sampled 15 woodlots in Clemson, South Carolina, to assess the invasion of M. bealei and other woody non-indigenous species (NIS). M. bealei invaded 87% of the woodlots surveyed and species richness of NIS on these woodlots varied from 5 to 14. Stepwise-multiple regression indicated that less canopy cover and older M. bealei predicted greater abundance of M. bealei , and that not all subdivisions were equally invaded (P < 0.0001; r² = 0.88). The impact of M. bealei on native flora and fauna may be considerable, and it is likely to continue to spread in the Southeastern United States. M. bealei should be recognized as an aggressive invader in the Southeastern United States, with the potential for negative impacts on native flora and fauna.     

Application of a photosystem II model for analysis of fluorescence induction curves in the 100 ns to 10 s time domain after excitation with a saturating light pulse

A mathematical model of photosystem II (PSII) events was used to analyze chlorophyll fluorescence transients in the time domain from 100 ns to 10 s after excitation with a saturating 10-ns flash, applied as a part of specialized illumination protocol, using preparations of a thermophilic strain of the unicellular green alga, Chlorella pyrenoidosa Chick (using both intact and diuron-treated cells). Analysis of simulation results has proven that particular attention should be given to flash-induced recombination processes, including nonradiative recombination in PSII, while subsequent charge transfer along the electron transport chain of thylakoid membrane can be adequately described by a single reaction of quinone reoxidation. The PSII model was extended by taking inhibition by diuron of the electron transport in the acceptor side of PSII into account, which allowed simulation of fluorescence induction curves observed in the presence of this inhibitor. The model parameters were determined (stromal pH, rate constants of nonradiative recombination, and the initial reduction state of the quinone pool) which provided adequate simulation of experimentally observed ratios of the maximal and initial fluorescence levels (F _m/F ₀).     

Plasma prolactin concentrations in breeding pied flycatchers (Ficedula hypoleuca) with an experimentally prolonged brooding period

This experiment explored the stimulatory effect of brooding newly hatched young on plasma prolactin concentration in male and female pied flycatchers, Ficedula hypoleuca. By exchanging offspring between nestboxes, one group of parents was exposed to 1- to 3-day-old nestlings for 12 days. Females in this group continued night-time brooding during these 12 days. The females, but not the males (who do not participate in brooding nestlings), after 6 days had higher plasma prolactin concentrations than control birds which had shown a 50% reduction in night-time brooding at this stage. By Day 12, however, prolactin concentration had decreased to the same level as in control birds, even though these females were still brooding 3-day-old nestlings. Female flycatchers given 3-day-old nestlings on the day their own eggs hatched showed an earlier reduction in night-time brooding and an earlier decrease in plasma prolactin than did control birds. An early decrease in prolactin was also seen in the males of this experimental group.